FEEDING CALVES

• Calf feeding

6.1.1  Aim of calf feeding

The aim of calf feeding should be to reduce the mortality (death) rate while maintaining a growth rate of at least 400 g/day. For bigger breeds (Friesian and Ayrshire) the aim should be to wean calves at 12 weeks at approximately 80 kg body weight.

The primary concern in rearing the newborn calf is to ensure it remains healthy. Feeding management addresses nutrient requirements and in the initial stages should be primarily directed at encouraging rumen development.

6.1.2   Stages of development of the calf rumen

calf feeding is divided into four phases, depending on the development stage of the digestive system.

When the calf is born, the rumen is not functional and forms only a small proportion of the stomach. As such the calf cannot digest complex fibrous feeds. The calf is thus fed on liquid feeds and low-fibre solid feeds until the rumen develops. As these feeds are mostly milk or milk by-products, which are expensive, early rumen development to allow feeding of cheap feeds is desirable. Early development is stimulated by feeding solid feeds. concentrate feeding has been shown to stimulate development faster than fibrous feeds.

Colostrum phase (1–3 days)

The calf is born with low immunity (protection from pathogens found in the environment) and is therefore susceptible to infections. colostrum is the first milk extracted from the mammary gland of the cow after calving. colostrum is a source of antibodies that protect the calf from these pathogens. It is therefore imperative for calves to get this milk immediately after birth as the rate of absorption is highest within the first 3 days.

Pre-ruminant phase (4 days to 20–30 days)

During the pre-ruminant phase, the calf rumen is still not functional and the calf can only take in liquids. The calf cannot digest complex carbohydrates or complex protein and thus only milk or milk by-products should be fed. Milk replacers should contain simple proteins. Rumen development starts towards end of this phase.

Transition phase (2 to 3 weeks before weaning)

Rumen development continues. In addition to liquids, the calf should be encouraged to consume dry feeds, especially concentrates, as they are known to accelerate rumen development.

Post-weaning phase

In the post-weaning stage, the rumen is fully functional and the calf can handle fibrous material. However, the calves should be weaned on high-quality pasture and fodder to maintain a high growth rate. Water should be made available ad libitum.

6.1.3   Calf feeds

Colostrum

Colostrum provides both antibodies and nutrients to the calf. Antibodies protect the calf against diseases the mother has been exposed to and their absorption in the digestive tract occurs for an extremely limited period (significantly reduced 12 hours after birth and very low after 24 hours).

If necessary, help the calf consume colostrum from a nipple bottle. If new animals are introduced into the herd just before calving, it may be necessary to vaccinate them against the common diseases so that they can develop antibodies. If for any reason the calf is not able to get colostrum from the mother, make artificial colostrum (see below), use stored (frozen) colostrum or use a contemporary mother.

Where possible, the calf should be allowed to suckle for at least 3 days before separating it from the mother. A supply of high-quality colostrum should be saved and frozen for use by calves from cows that die at birth or have mastitis or milk fever.

Preserved colostrum

Exotic breeds produce colostrum in excess of the calf’s requirement. As colostrum has a high nutrient content, do not discard this excess but store it for feeding the calf later.

The colostrum can be preserved by several methods. Freezing is ideal but is not feasible on small-scale farms without electricity. other methods include natural fermentation (store at room temperature) and use of preservatives (formaldehyde 0.05%, or formic acid 0.1%).

Before feeding the calf, mix the colostrum with warm water at the ratio of 2 parts colostrum to 1 part water.

Artificial colostrum

If the mother does not produce colostrum, artificial colostrum is recommended. Artificial colostrum does not provide antibodies but is rich in nutrients.

The recommended composition of artificial colostrum is

1 egg (beaten) + 400 ml fresh warm water + 600 ml whole milk + 1 teaspoonful castor oil or cod liver oil.

Feed this mixture 3 times a day for the first 3 days of life. A calf that has not received any maternal colostrum requires much more care.

Milk

Since milk is the saleable product from a dairy farm, it is necessary to switch young calves to cheaper feeds as early as possible. However, the diet must be able to promote health and growth.

Calves should be fed milk at the rate of approximately 10% of their body weight (reducing this as the calf starts to consume other feeds) to achieve good growth rates. Feed at body temperature. The milk can be mixed with other milk products (whey or skim milk) to lower cost. Whey (powder or liquid) can be obtained from creameries making cheese and skim milk (powder or liquid) from butter makers.

Milk replacer

Before using saleable milk or milk replacer, make proper use of stored excess colostrum. Use milk replacer only if it has an economic advantage over milk. Compare on the basis of dry matter. For example, Friesian milk contains about 26% protein and 30% fat on a dry-matter basis while most milk replacers contain about 23% protein and 15% fat.

Calf starter

The starter contains a slightly higher fibre content than does the pre-starter, a highly digestible, highly palatable feed specifically formulated as the first dry feed to allow early intake. At this stage the calf is consuming little milk and its rumen is still not fully developed. The starter should contain 18% crude protein, low fibre, 0.7% calcium, 0.45% phosphorus and vitamins A, D and E.

Roughage

offer calves only high-quality forages early in life and supplement with concentrates (calf starter). If hay is used, it should be of high quality, fine texture, mixed with legumes and fed ad libitum. If calves are on pasture, it is best to always graze them ahead of adults

to avoid calves consuming parasite eggs or larvae that are normally shed through the faeces of adult animals onto pastures.

Common roughages offered to calves include sweet potato vines and freshly harvested, wilted lucerne.

Water

Calves should be offered fresh water in addition to milk. Lack of drinking water slows down the fermentation process of the starter in the developing rumen, which in turn slows down development of the rumen lining and it takes longer before calves can be safely weaned.

It is estimated that efficient conversion of feed into body mass growth requires about 4 kg of water for each kilogram of dry feed calves eat. Lack of water thus lowers feed conversion. Age and stage of development determine how much water calves require:

• From 1 to 6 days of age, calves may drink large quantities of water when it is first presented. This novelty water consumption pattern rarely persists more than a day or two as long as water is offered ad libitum.
• Calves less than 3 weeks old do not need a lot of water but a steady supply of clean, fresh water is recommended.

Between 3 weeks and weaning, calves’ water consumption usually increases and water should be offered ad libitum.